1. Field of the Invention
The present invention relates to an electrophotographic image forming device, such as a laser beam printer, a copying machine, or a facsimile device. More particularly, the invention relates to a process unit detachably loaded into the image forming device and a structure of the image forming device for receiving and accommodating the process unit.
2. Description of the Related Art
Conventional image forming devices, such as a laser beam printer, use a process unit. The process unit is, for example, a combined unit of a photosensitive unit and a developing unit. The photosensitive unit includes a photosensitive drum and a charger. The developing unit includes a developing roller and a toner cartridge containing developing agent (toner) therein.
During a printing operation, the developing roller is urged against the photosensitive drum, so that the developing roller transfers toner onto the photosensitive drum. Also, a transfer roller is urged against the photosensitive drum.
For the sake of maintenance and for facilitating paper jam removal, the process unit is detachably mounted on the image forming device. That is, the process unit is unloaded from and loaded into the image forming device when a paper jam occurs, for example.
U.S. Pat. No. 6,101,350 proposes horizontally loading the process unit. The horizontally loading type requires a locking mechanism to prevent the loaded process unit from being accidentally detached. In order to withstand a strong detaching force imparted upon the process unit, a rigid locking mechanism is needed. However, the image forming device cannot be structurally simplified and made compact in size and also the cost of the image forming device cannot be lowered if the rigid locking mechanism is employed.